Electrical heating unit



1936- R. H. JORDAN 2,041,352

ELECTRICAL HEATING UNIT Original Filed Feb. 21, 1934 g 98 WITNESSES: Q INVENTOR az z Patented May 19, 1936 UNITED STATES PATENT OFFICE ELECTRICAL HEATING UNIT Richard H. Jordan, Springfield, Mass., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, :Pa., a corporation of Pennsylvania 4 Claims.

My invention relates to electrical :heaters and it has particular relation to an .improved form of construction for heating units adapted for use in electrical hand-driers and other comparable heating devices.

This application;is a division of a copending application Serial .No. 712,349, filed :FebruaryZl, 1934 and assigned to the Westinghouse Electric 8: Manufacturing Company. In that application there is disclosed and claimed anrimproved electrical hand-drier which embodies a number of advantageous features. The subject of the present application is an electrical heating unit of improved construction which is especially suited for use in the mentioned hand-driers as well as in a wide variety of other comparable heating devices.

Generally stated, the object of my invention is toimprove the construction of electrical heating unitsof the named variety.

A more specific object is to lower the cost and facilitate the assembly of such heating'units.

Another objectis to so construct the unit as to facilitate its replacement in the discharge opening of the blower ,or otherfiuid circulating device with which it is used.

.A still further object is ,to provide a construction in which the heating conductors are uniformly positioned both circumferentiallyandaxially of the cylindrical passage through which the air to be, heated is blown.

My invention itself, together with additional objects and advantages thereof, will best be understood through the following description of a specific embodiment when taken in conjunction with the accompanying drawing, in which:

Figure l is a partially cut away view in side elevation'of one type of heating device for use in which the heating unit of my invention is especially adapted,

Fig. 2 is a plan view of the improved heating unit of the-present invention,

Fig. 3 is a view in side elevation of the heater of Fig. 2,

Fig. 4 is a side elevational view of one of the resistance wire supports which forms a part of the heater of Figs. 2 and 3,

Fig. 5 is a view in end elevation of one of the support spacers incorporated in this heater, and

Fig. 6 is a view in side elevation of the spacer of Fig. 5.

Referring to the drawing, the electrical handdrier depicted in Fig. 1 comprises an air blower In which is supported in an angle iron frame comprising upright members l2 suitably braced and interconnected by cross arms. Underneath the blower, which may be of any one of a number of commercially available types, is mounted an electric motor 20, which drives the blower by means of an endless belt 22. The blower comprises a cylindrical air discharge passage .28 in which is positioned the electrical heating unit of the present invention. The construction of this unit is more completely shown in the following figures, only the protruding top portion .25 thereof being represented in Fig. 1.

Operation of the illustrated hand-drier is controlled by means of a treadle actuated switch 80. Surrounding the equipment just described is a suitable casing 36 which completely covers the draft producing mechanism, and, in addition, forms above a partition member .40 a pressure chamber or compartment into which theheated air is blown and from which it is discharged for drying purposes through a suitable opening in the top thereof, through an adjustably mounted discharge fixture 42. Energizing current for the blower driving motor and the .air heater is derived through a connection with the lighting or other power supply circuit established by means of a flexible cord 15. The electrical hand-drier just described represents only one of anumber of forms of heating devices to which the improved heating unit of my invention about to be described may be applied.

lnimy improvedheating unit, the coils 90 of heating wire are, as is best indicated by Fig. 2, uniformly distributed throughout the air passage defined by the unit shell in a manner not to unduly obstruct the fiow of air therethrough. The illustrated unit is adapted to be positioned, as before explained, in the cylindrical outlet passage 28 of the blower [0 of the hand-drier of Fig. 1.

In the construction of this heating unit, a cylindrical shell 30 is formed from sheet metal, a fiat strip of which is first cut to the desired dimensions and then bent into the circular contour of the cylinder. In this position the cooperating or overlapping edges of the sheet are spot welded or otherwise secured to each other, this junction being indicated in Fig. 3 by the area of overlap 92. In this original fiat sheet are also out two parallel oblique slots 93 and 94, each of which in the assembled cylindrical shell 30 is spiral in form as is also indicated in Fig. 3.

The cylindrical shell having been assembled porcelain heating wire supports 96, a side View of one of which is shown in Fig. 4, are then inserted in the spiral slots 93 and 94, they being spaced from each other by means of suitably slotted spacers 9B constructed of sheet metal. An end view of one of these spacers is shown in Fig. 5 and a side view in Fig. 6. At the bottom of slot 94 and at the top of slot 93 are positioned terminal bolts 91 which secure the two ends of the coil of heater wire 90. This coil is progressively threaded among the specially spaced supports 96 in the manner indicated in Fig. 2. Energizing circuit connections with the coil are made through the terminals 91 by means of conductors 95, which are threaded through a porcelain bushing 99 carried by a top ring member I00 which surrounds and is secured to the upper portion of the cylindrical shell 30 by an attachment effected by means of bolts I03 to a pair of shell ears I02.

In assembling the described heater unit, the coil of heater wire 90 may be threaded through the insulator supports 96 before their insertion into the slots in the cylindrical shell, in which case this preparatory threading operation may readily be accomplished by arranging the insulators which are to go in each of the two spiral slots in parallel rows on a flat surface, which rows are spaced substantially by the diameter of the shell and then threading the coil of heater wire in zig-zag fashion progressively through these supports. When spacedly placed in the two opposing slots, the resulting diversification of the individual branches of the heater coil length shown in Fig. 2 will be obtained and a stream of air in being blown through the cylindrioal shell 30 will be uniformly and effectively heated without receiving undue physical obstruction.

In installing in the cylindrical discharge opening 28 of the blower I0, the heater unit may be secured to the top rim surrounding the opening by means of screws I06 which are accommodated by the holes H11 in the heater rim I00.

It will thus be seen that the construction just explained requires a minimum amount of materials and assembly effort, and is, therefore, highly economical. The completed heating unit furthermore is of such a nature as to permit ready replacement in case of failure of the heating wire coil. Because of the uniform positioning of the conductors in the air passage, their effectiveness in raising the air temperature is maximum and the obstruction offered thereby to the flow of air through the passage is kept at a minimum.

Although I have shown and described a certain specific embodiment of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the scope of the appended claims.

I claim as my invention:

1. An electrical heating unit adapted to warm a fluid when blown therethrough comprising a cylindrical shell member having at least two spaced oblique or screw-like slots out in the wall thereof, a plurality of insulator members spacedly positioned in each of said slots, and a heating conductor supported inside of the shell by being progressively threaded between the insulators positioned in said slots.

2. An electric air heater comprising, in combination, a cylindrical sheet metal shell having at least two oblique or screw-like slots cut in the wall thereof, a plurality of insulator members spacedly positioned in each of said slots, and a heating conductor progressively threaded among said insulators in a manner to cross and re-cross the shell interior through relatively uniformly diversified paths.

3. An electric air heater comprising in combination a cylindrical shell having a plurality of spiral slots cut in the wall thereof, a plurality 01' insulator members, each of which is provided with an annular recess of dimensions corresponding to those of the shell slots, installed in each of said slots by being slid in from the open end thereof, similarly recessed spacer members positioned intermediate adjacent insulators in each slot to maintain a given separation therebetween, and a heating conductor progressively threaded among said insulators in such a manner that it crosses and re-crosses the shell interior through rela tively uniformly diversified paths.

4. An electric heater comprising in combination a cylindrical shell having a plurality of spiral slots cut in the wall thereof, a plurality of insulating supports spacedly positioned in each of said slots, a heating conductor progressively threaded among said supports in a manner to cross and recross the shell interior, and a pair of terminal bolts, which protrude through the wall of said cylindrical shell at opposite ends thereof, adapted to secure the two ends of the heating conductor and establish a connection thereof with an energizing circuit.

RICHARD H. JORDAN.

Ill 

